Lateral DMOS transistors that include one RESURF region in a RESURF drift region are known. Such devices include either two RESURF regions of opposite conductivity (double RESURF), or one RESURF region of one conductivity and two RESURF regions of another conductivity (triple RESURF). A lateral RESURF LDMOST derived from the conventional RESURF LDMOST is disclosed in D. R. Disney, A. K. Paul, M. Darwish, R. Basecki and V. Rumennik, “A New 800V Lateral MOSFET with Dual Conduction Paths,” International Symposium on Power Semiconductor Devices and Ics (ISPSD), pp. 399-402, 2001.
A device according to the present invention includes two RESURF regions of one conductivity, and two RESURF regions of another conductivity disposed between the base region and the drain region thereof. Thus, a device according to the present invention is a quadruple RESURF device.
A device according to the present invention is believed to have an improved trade-off between the on-state resistance (Rdson) and the breakdown voltage (BV) over the prior art. For example, a factor of two reduction in Rdson is expected. The significant reduction in Rdson will result in smaller devices for a given current carrying capability which in turn reduces parasitic capacitances and improves speed of the performance of the device.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.